999999999999778 has 16 divisors (see below), whose sum is σ = 1551725424217080. Its totient is φ = 482758220511616.

The previous prime is 999999999999659. The next prime is 999999999999809. The reversal of 999999999999778 is 877999999999999.

It can be written as a sum of positive squares in 4 ways, for example, as 824701526158689 + 175298473841089 = 28717617^2 + 13240033^2 .

It is a super-9 number, since 9×999999999999778⁹ (a number of 136 digits) contains 999999999 as substring.

It is a self number, because there is not a number n which added to its sum of digits gives 999999999999778.

It is an unprimeable number.

It is a polite number, since it can be written in 7 ways as a sum of consecutive naturals, for example, 70668150 + ... + 83630062.

Almost surely, 2^{999999999999778} is an apocalyptic number.

999999999999778 is a deficient number, since it is larger than the sum of its proper divisors (551725424217302).

999999999999778 is a wasteful number, since it uses less digits than its factorization.

999999999999778 is an evil number, because the sum of its binary digits is even.

The sum of its prime factors is 14292101.

The product of its digits is 110712378300552, while the sum is 130.

The spelling of 999999999999778 in words is "nine hundred ninety-nine trillion, nine hundred ninety-nine billion, nine hundred ninety-nine million, nine hundred ninety-nine thousand, seven hundred seventy-eight".